Appendix M - Color Separation for Printing

CMYK Plate Separation Dialog

Overview

Creating color separations is a process that depends on a number of factors, from the source image, to the paper and the inks used, and all the steps in between. While it is definitely a science, not an "art", the process is complex enough and involves enough factors under the control of your print shop (and not you!) that good (or great!) results are reliably obtained only by those who have had some experience. So if this is your first foray into color separation for printing, be prepared to make more than one try at this - even if you're the smartest person you know.

About the Process

Beginning with a standard RGB image, the additive red, green and blue data is transformed into four (or very rarely, three, there is no black channel in this case) subtractive color channels: Cyan, Magenta, Yellow and Black. Or, C, M, Y, K: CMYK. These four subtractive colors can be reproduced on paper by inks of the same color (or as close as possible to the same colors.)

Key: Additive colors are colors that add together over black to create colors, where the addition of all the maximum color values makes white. This is true for an RGB image; adding 100% red, green and blue results in white. Subtractive colors are colors that subtract from white to create colors, where the subtraction of all the maximum color values makes black. This is true for an CMY image; subtracting 100% cyan, magenta and yellow results in black. Ermm... So... Why use black at all? That's because the black that is created by CMY inks is sort of... muddy. It looks more brown than black. The math works fine, so CMY images on screen can be perfect, but the actual inks just don't mix that well when there's a whole bunch of ink of all three colors. So where an image has blacks, greys and darkish colors of all tonalties, typically, the CMY inks are not used as much, and instead black ink is used to "boost" the image into a darker appearance. This results in very high denisity (good looking) dark colors of all types. One of the key elements of color separation is to decide exactly where to use black ink, and how much to use, and what that means in terms of reducing use of the CMY inks.

Offset Lithography Schematic

for just one of the four color plates

So it is that four "monochrome" files that contain images which carry intensity information that describes how much to use of each of the cyan, magenta, yellow and black inks are provided to the printer. Then the printer "screens" or "halftones" the density information into dots that can easily be printed. Finally, these dots are placed on a metal plate (the Lithoplate Roller), which, through a really neat mechanical process involving other rollers, ink, water and even knives, creates a reproduction of the picture from your original RGB image.

It's really fun to watch - if you ever get a chance, try to visit your print shop (but warn them first!)

That's the basic process. But it's not really that simple, because the CMY ink colors aren't as "pure" as the colors in the channels, because the inks interfere with each other on the paper, because the colored inks don't make very good blacks when combined in equal amounts, and because each of the components: the paper, the ink, the press that prints the ink to the paper, and how the subject matter of the images is turned into "dots" (screening or halftoning) all affect the output. Whew!

All of this means that the objective of creating high quality color separation plates intended to be used on an offset press can only be reached by accomodating all of these factors, and more. And that's what all that "stuff" in the dialog is there to help you do.

How to Approach this Appendix

In the following sections, each of the various issues is covered in some detail. It is very complicated - there's just no way around that - so take your time, read each section as many times as it takes to "wrap your head around it", and feel free to question your print shop or our

technical support people

on anything that seems unclear after you've studied all the material provided. Just keep in mind this is a highly technical area and you have to make a significant effort to deal with it at all.

Work with your Print Shop

This point cannot be emphasized strongly enough. Your print shop knows (or should know) all about the process of preparing image files for printing. They'll be converting the files you save to the film and then the film to the color plates themselves, and finally using the plates and screens to transfer the colored inks to the actual paper.

Any good print shop should be able to give you the facts and figures you need to set up WinImages F/x to give you fabulous results. WinImages F/x provides the settings you really need to control the parts of the process you as the image creator are responsible for, and allows you to save your separations in any image format you like, which means the output files can be made to be compatible with almost any print shop. Then they can do the part of the job that they are responsible for well.

Plan the Separation

Separation Format

Ask your print shop: What image file format should the plate separation images be saved in? TIFF is common, but any lossless format is appropriate. Don't use JPEG, and don't reduce the number of colors in the separated data files. If you're going to write 8-bit output files (this is common), set the output color reduction dialog to use a grayscale palette and no dither.

Image Pixel Resolution

To prepare images in the optimum resolution for your printing project, you'll need to know what the Screen Frequency will be for the output plates. Ask your print shop. Then create your output images with a pixel resolution per inch of between 1.5 and 2 times the screen frequency. So (for instance), if the screen frequency is 100, then an image resolution of 200 DPI is excellent. If the image is ten inches high, it will have to be 2000 pixels high (that's 200 pixels per inch.) At a minimum, it would be 1500 pixels high.

If you use an image of less than DPI = 1.5 times the screen frequency, you'll begin to see "stair-stepping" on the edges of elements of the image. If you use an image with a higher resolution than DPI = 2 times the screen frequency, you'll begin to lose pixels - some won't show up on the output plate at all.

DPI is literally "Dots Per Inch". So if you know you'll need 200 dpi, and you want the image to cover an area three inches across, you'll need an image that is 600 pixels wide. The math to figure this out is easy enough - just multiply the DPI times the number of inches you want to cover.

The actual screen frequency can vary widely, depending on what you're trying to print. Talk to your print shop about what would work best for what you're attempting.

Image and Bleed Areas

You need to remain aware at all times of what parts of the image are meant to go on the paper, and what parts will be cut off. If you expect to "print right up to the edges of the paper", then you need to talk to the printer about the amount of the image you'll need to provide in this bleed area.

Positive or Negative Plate Files

Just ask your print shop what they prefer.

Multiple Images

Typically, you'll get better results if you create separations for each image on a page independently. If you create a separation that contains all the images on one page, you definitely run the risk of a poorer quality result.

Plate Separation Settings

UCR and GCR

UCR stands for "Under Color Removal". GCR stands for "Grey Component Replacement."

Note: If you want to use only UCR or GCR processing, enter zero in the setting you are not going to use. In other words, to use the setting for GCR, enter zero for UCR. You probably don't want to use both settings unless your printer specifically says that's ok, or you're so technical you completely understand the implications of the two different kinds of ink management. You definitely can use both, and it definitely can be of benefit to you, but it is not "basic" use!

UCR is a process by which black ink (the K channel) is used to darken areas that are either grayscale, or where colors are fairly neutral. This works well for images that need to keep a tight rein on grayscale values.

GCR, in contrast (pun intended), uses more black ink on colors that are not neutral. This tends to work better for images that have dark colors that are nonetheless quite pure - they seem richer and more vivid with a GCR separation.

WinImages F/x allows you to use either, or both(!) processes; but you need to talk to your print shop and see what they suggest. The choice between the two is also affected by the inks in use, the paper that the image will be printed on, and perhaps limitations of the print shop - some will definitely get better end results with the process they suggest.

Tip: The percentage settings in the dialog for these two features act to control the maximum amount of black ink (K) that will be output to the K separation using the method(s) that is/are non-zero. Many presses have trouble generating screens denser than 75%, and so we suggest that you view any setting higher than 75 for either UCR or GCR as inadvisable unless your print shop assures you such a high setting is ok. In some software, such as Photoshop ®, these settings are called the "Black Ink Limit" settings, and typically you would choose UCR or GCR and then set a single setting for the Black Ink Limit. WinImages F/x's plate separation engine is more sophisticated than this in that it allows you to use both UCR and GCR. However, to get the same results as those other programs, you simply set the unused separation mode to 0 and the one you do set will act as the Black Ink Limit.

Undercolor Threshold

If you're using UCR, then this setting is used to limit the total amount of ink that (eventually) is placed on the paper. The default is 300%. It is common to see maximum ink limits equal to four times the Black Ink Limit, so 300% is four times a 75% UCR setting. If the UCR setting for Black Ink Limit was 70%, then as a rule of thumb, you could reasonably expect the Undercolor Threshold to be 280%. As always, consult your print shop to see what they prefer to use.

Remember, for the Undercolor Threshold to be applied, you must use UCR.

Ink Corrections

In a perfect world, inks would be pure colors. Alas, it's just not so.

Cyan (blue) inks contain trace amounts of magenta pigments, and magenta inks contain trace amounts of yellow pigments. Professional yellow printing inks, however, are quite pure and do not require compensation.

WinImages F/x's printing separation allows you to compensate for the impurities in the cyan and magenta inks. As usual, you'll need to consult your print shop for suggested settings - this depends entirely upon the inks used in the final printing stage.

Dot Gain

Dot gain, also known as "Tone Value Increase" (TVI), is really a fancy name for a simple idea: When you put a medium to heavy dot of ink on paper, it spreads out. That makes the spot larger, and perceptually darker, than intended. The word "gain" means to increase, and that's what happens - the dot "gains" in size. And remember, when a press prints an image that has been screened or halftoned, it's printing nothing but dots!

The tricky thing about dot gain is that the larger the amount of ink put down for a dot, the more gain results. So for a small dot - in an area of an image where the ink coverage is light - there will be little or no dot gain. In fact, it tends to go the other way. Really small dots of ink can be absorbed into the paper, and so they make a smaller spot than intended, resulting in areas that are too light. Also, for very large dots, although dot gain occurs, because the dot was large in the first place, the percentage change is not that high. It boils down to dot gain having the most visual effect at a dot size that would, if perfect, provide 50% grey.

Here's an example showing how a 50% screen can go to 70% as a result of the effect of dot gain:

 

50% actual screen resulting in a 70%


effective screen due to dot gain

WinImages F/x's dot gain correction, in the final analysis, involves lightening medium to fairly heavy areas of ink coverage. This tends to result in an image that will look "washed out" if you recombine the CMYK plates using the add as CMYK layer modes, but the dot gain at the printing press reverses the effect and you get a good final image this way, so don't be concerned if you see this effect. This only works correctly, of course, if you've got the right setting.

Also, as you might well imagine, the press, screens, inks and papers used can greatly affect how much dot gain is a factor for any one image or project. For instance, the greater the number of lines in the screen, the more dot gain is a factor. So this is definitely one of those issues that you want to keep aware of on a per-print-shop basis!

Because a CMYK color separation actualy isolates the inks - the four plates are literally used with four matching inks - even manual adjustments for ink coverage are really very easily made to the separated results. For instance, in WinImages F/x, you could use the Histogram or ChannelMap operators for custom adjustments, or even the Gamma operator for a "pre-cooked" curve that would do a good job. Or you could use the Scripting operator to create repeatable, precision custom results. But... making the correct adjustments - now, that is the trick!

Rather than trying to struggle through this manually, most people will be better off using the simple setting in the plate separations dialog. This controls a "knee" at the 50% intensity point that reduces the ink output to the percentage specified at the 50% point, and linearly returns to zero percent at both ends of the intensity range. No compensation is applied for dot loss, but dot gain may be adequately controlled with the correct setting.

First (of course!) talk to your print shop. They should be able to give you some figures. 7% gain in the midtones is a decent starting assumption if no one is willing to hazard a guess for you. If the resulting image is too dark in the midtones, increase the dot gain setting. If it is too light in the midtones, decrease the dot gain setting. A setting of zero is no dot gain. We should also point out that the 20% dot gain example above would usually be a very high value; you're more likely to see values under 10%. But with fine screens, you might even see more.

Warning: Don't try and use dot gain to increase or decrease overall image brightness; dot gain primarily affects the midtones and you'll almost certainly end up with results you don't like this way.

Save your Settings!

Once you have settings that work well for a particular paper, ink, and print shop, save them! Name them so you can easily find them and this will enable you to reliably produce high quality output again and again using these particular components: paper, ink, press, and screen frequency, all at this particular print shop. This point cannot be emphasized too strongly - it can be quite a job to get everything set just right, so saving your settings under an easy to recognize name can save a lot of time for you later on.

Unsupported CMYK Mechanisms - what, and why

UCA - Under Color Addition

WinImages F/x does not support UCA.

UCA is a process that adds cyan, magenta and yellow where black ink is present in a CMYK composition.

UCA is generally not desirable in offset printing. Furthermore, unless the dark areas are absolutely devoid of those ink colors (meaning the region must actually be greyscale in the first place), using UCA will almost certainly destroy the color balance of the region.

The idea of UCA is that adding the colored inks in order to replace the black inks changes the underlying black to a black that is brownish, and that, in the view of some folks, can improve the occassional photo. Generally speaking, for the vast majority of images and projects (sets of images) it is a terrible idea, and WinImages F/x does not support it at all. But - if you really want browns in the areas where the image is black, then use the color key modifier to limit application, and fill the darkest regions with the brown you want prior to separation.

Halftone Creation

WinImages F/x does not create halftones.

Optimum halftone creation is a very tricky endeavor for the operator. It is intimately related to both the actual screening and the specific printing press in use, and your print shop is best qualified to perform both of these steps of the printing process. It is a fact that more low quality printed output results from improper halftoning than any other single step.

The plate separations output from WinImages F/x are ready for halftoning by the print shop. They contain pure ink density information.

Trapping

WinImages F/x does not automatically "trap".

Trapping is a process used to compensate for misregistration of the color plates in the printing press. This can cause gaps to appear between edges of areas that have colors that use different plates; if the cyan plate is a little off from the yellow plate, for instance, an image of the sun (yellow) in the sky (blue) the blue may overlap the yellow on one side and present a gap on the opposite side and create unintended ink mixing, or "mud."

You can, if absolutely necessary, compensate for this by blurring the edges of the sun and/or the sky in the specific color separation plate or plates after the separation has been created. In taking this approach, keep firmly in mind that the only places where you should try to compensate are where plates differ markedly from one another. Areas of continuous ink coverage don't need (and should not receive) any compensation even if the edges are sharp. Look for sharp transitions in color that cause one separation to suddenly pick up and another to leave off in ink coverage.

This is by far a better approach than "automatic" trap generation because trapping, by its very nature, reduces the quality of the actual image data, which (of course!) you don't want. It is worth noting that some print shops always seem to want traps, and others don't - and of course, the shop that doesn't need traps to get good results is the one to go with.

While trapping is presented by software that supports it as a means to "solve a problem" (plate misregistration) it does so always at the expense of the printed image quality. Problems such as hatching and muddy edges are typical (though unintended) results of trapping. We feel that the best approach is to solve the actual problem (misregistration) rather than introduce a new one (blurring plate edges where colors overlap) to solve the first.

1 - Overlap caused by misregistration 2 - Gap caused by same misregistration Trapping would fill the gap at (2), but would also exacerbate the muddy edge created by the overlap at (1). A much better solution is to get the plate alignment fixed. Watch for this type of error in magazines and books; it is the mark of a shoddy and careless print process. Author : BlackbeltSystem

Advertising As A Fundamental Brand Promotion Tool

Advertising is important and essential for any brand owner to drive sales for the product or service. Advertising provides a major contribution to brand competition in the market. Advertising not only provides information about a product or service but also promotes innovation. Besides advertising also facilitates consumer satisfaction. The hidden fact is that no brand can progress without advertising. Big and small companies, individuals of all walks of life, major and minor events, concepts etc lay their base on advertising to get recognised in the market. Government and NGOs even use advertising to raise health awareness such as Conjunctivitis, Dengue, Swine flu etc.

The objective of an advertising campaign varies from one company to another. Some companies indulge in advertising to promote their product or service or to create buzz about their product while some companies indulge in advertising activities to launch new product in the market

Today in India, Advertising is a big business for every single organization. With a uniform economic stint in the country, Indian Advertising industry has witnessed a prominent globalization. Also, with the inception of various divisions, the advertising industry has undergone a sea change. Indian consumer's deep pockets and blooming markets for ad-spends have touched new heights in India. Advertising India companies are creating stories and brand experiences in a way that engages and involves the target audiences with a mass appeal.

The history of advertising India is traced back to the early 20th Century when the first advertising agency- B. Datram and Company was established in 1905. Since then, Advertising is the most common tool widely used by advertisers and brand owners. Amongst the various means of advertising, outdoor or OOH advertising is the oldest and yet the most effective tool for brand promotion. Also known as out of home advertising, this type of brand promotion provides a flashy communication to audiences simultaneously rendering a captivating message to the TG. Outdoor advertising or OOH advertising or Out of home advertising, whichever name one calls it, offers a discreet tool for brand promotion.

OOH Advertising or Out of home advertising campaigns have to be tactfully carried out. One popular subset of outdoor advertising is Airport advertising. Considered as one of the budget friendly mediums of brand promotion, airport advertising reaches its target audience in an effective manner. Airport advertising offers low cost mode of advertising as compared to other means. Those people who are ‘on the go' tend to spend quality time at the airport and it is one reason why airport advertising is one of the most effective means. Exclusive features about airport advertising include its high-glamour look, attention-grabbing duration, high-tech etc. Airport is a place where people from all across the world arrive or depart from, hence, this mode of promotion is an ideal means for promoting a brand or service to potential buyers who are on transit mode.

Reference Website: www.tdiindia.com

Black vs. Black

Not every black is same. Some blacks are different than others. What am I talking about? Fair question.

When you do four color process separation from your RGB images for print, you can control the amount of the different colors of cyan (C), magenta (M), yellow (Y) and black (K) to print your blacks. By default PS will convert your RGB black to C91%, M81%, Y81%, K88%. But this depends on your Color settings in PS. Why only 88% balck and not 100%? That's because every printing house has a limit to how much ink they can apply to that particular paper that you choose. Usually you can't go above 350% of total ink. It's usually better to give up some black so that we can print more colors and still fit into the 350% barrier. So, the separated CMYK black is made up of all four colors and it has a very high density of color.

You may wonder, why not print 100% black and we are done? That's a good question and this is exactly what we will do. 100% Black doesn't produce a deep black that you might want to achieve when printing four color process images and the 100% black has much less density, but it's still gives complete coverage.

You can play with these two blacks to create amazing effects in print without any extra cost of lamination or UV varnish. The two different blacks will react differently to different lighting conditions, so you will be able to make out the difference quite easily.

You can even take this further and try to mix other blacks such as 100%M and 100%K to get a black with a purple cast.





While you can't reproduce the printed effect on the screen, this is a simulation of what you'll get.


[tutorial and images © Ivan Raszl of CreativeBits]

Calibrate and Profile Your Monitor Before Printing

So you have bitten the bullet. You've decided that your crisp new product collection is just too special to be advertised with amateur photography, so you've called in a photographer to help record your products finest visual assets and help enhance your corporate brand image.

The disk arrives and as guessed the photography is flawless! All you need to do now is enhance the images a bit in Adobes Photoshop, FTP them to the printers and then await delivery of your beautiful new brochure.

Your brochure comes back from the printers but all is not Ok! The photography looks nothing like it did on your monitor and now your products are sporting a rather unwanted yellow caste.

This is an really prevalent concern and one I hear customers agonize about on a regular basis. The natural response would seem to be, 'blame the photographer', after all they were the suppliers of the original image files. But in truth it is most likely to one of or a mixture of the following issues:

1. Coarse Image Editing.
Inexperienced or incompetent Photoshop users will often engage in excessive and damaging image manipulation methods that will often result in poor quality printing.

2. Conversion to CYMK.
The image files your photographer provides you with are commonly in a RGB colour space and will need conversion to a relevant CYMK colour profile before printing. The picture files will require careful colour conversion and ideally proofing if exact colour accuracy is needed. Generally a professional designer or pre-production house will carry out this procedure but if executed badly the resulting prints can diverge immensely to what you saw on your screen.

3. Absence of or Insufficient Monitor Calibration and Profiling.
This is the big problem and the one that I suspect produces the most discontentment and problems. If your monitor isn't properly calibrated or indeed you simply use the manufacturers canned factory settings, there is a good possibility that your monitor is deceiving you!

Monitor Calibration is the method of altering your monitors controls to achieve the most neutral display possible, including modifying its luminance (brightness), white point (colour temperature) and gamma settings. If you don't work with photos on a frequent basis or you hire a graphic designer (who understands the importance of strict colour management) to do your pre-press work then you may well choose to simply alter your monitors controls manually, nonetheless remember not to change the image files as what you observe on your screen will be different to what your designer and printer sees! In any case I strongly advise that you invest in some basic monitor calibration apparatus that will come bundled with compatible profile software. You won't have to invest thousands, indeed for the price of a full set of inkjet cartridges you'll be able to buy a basic calibration device, but it will transform your digital workflow and give you the end results you deserve.

These relatively cheap devices will calculate your monitors imperfections and in combination with the software will work out a profile that is unique to your screen. Think of this profile as a 'filter' or 'mask' that once utilized to your screen will eradicate any imperfections and will give you a completely neutral view. This unique profile is then saved to your computers relevant libraries.

In conclusion when working with professional images on a recurring basis then I highly urge you invest in some basic monitor calibration equipment. Why spend good money on getting your photos shot professionally only to subsequently ruin them by editing on an poorly calibrated monitor?

Reference Website: ArticleBase.com

Bit by Bit: Why Your Photoshop Color Separations Are Wrong -- and How to Fix Them

Recently I got involved in a project studying the gamut of color available printing with CMYK (cyan, magenta, yellow, and black) inks versus that of several expanded-gamut printing processes. Expanded-gamut processes are those that use more than the typical four ink colors to express color images with brighter greens, reds, and blues. Pantone's Hexachrome is one example of an expanded-gamut printing process.

When I queried the printer who will be testing the colors in the study about how he wants his color separations made for traditional CMYK pigments, he responded that I should "just make them with Photoshop." When I asked for detail, he said, "Just pull-down the Image menu, then Mode, and then pick CMYK."

And right there is the crux of a problem that besets our industry: Most of us are converting to CMYK wrong. The method he described would result with the wrong default CMYK profile set. That he did not state exactly how to make a separation for his exact printing process indicated to me that he was working with the default settings in Photoshop. That worried me -- and made me think.

The SWOP Meet

I am going to stick my neck out here and guess that as many as 90 percent of Photoshop users in North America (I'll focus on this continent for my assertions in this article) make their color separations wrong. That's because Adobe Photoshop is set by default to make CMYK color separations with the SWOP profile. And, I will also bet that fewer than one percent of Photoshop users should be using SWOP for their separations when there is a far better way to do it located in the same Photoshop folder of available profiles.

Now it's possible that some of you don't know what SWOP stands for (thereby adding to the problem): SWOP is the Specifications [for] Web Offset Publications, a North-American standard adopted by the advertising industry, the prepress industry, and a number of publications printers. It is specifically directed to Web Offset Publications -- and I'm not talking about the World Wide Web, either.

I know we all read web offset publications ("Newsweek" and "Sports Illustrated" are two good examples), but few of us prepare artwork for web offset publications. Of all the designers in my circle of friends and associates, only one produces artwork for web offset. Most are busy preparing for sheet-fed offset, which is the means by which most jobs are printed in the world (web wins in the volume category, but certainly not in the number of jobs). That number includes the printer testing the colors in our expanded-gamut study. We were indeed preparing files for a sheet-fed press.

Yet, I'd wager that most of make separations as if we printed to web presses, and we don't even realize it's a problem.

Photoshop's Dark Ages

How did this come to be? Way back in the Dark Ages (defined as 40C, 30M, 35Y and 100K), Adobe Photoshop assumed that all the color that was reproducible in any document had to be within the gamut of color that could be displayed on the monitor. This assumption was not only incorrect, but it caused Photoshop to be derided by prepress professionals (especially those who had access to very-high-end equipment including drum scanners and proprietary prepress computers that could handle the full gamut of CMYK for quality printing). These experienced craftspeople noticed that the color that came from Photoshop was not as rich as the color produced by their more advanced prepress technologies.

Several people on the Photoshop team noticed it, too. Led by Chris Cox, a member of the software development team for Photoshop, the group came up with a plan to give Photoshop a better grasp of color. The result was Photoshop 5.0, which, in October 1998, decoupled the color in the image from the color on the monitor for the first time. They developed and shipped the first version of Photoshop that used what is called the Working Color Space, effectively an ICC profile that describes a triangular space inside of which an image's colors reside while the observer looks at a monitor with an often-smaller gamut of colors (see Figure 1).

Figure 1: The gamuts of monitors, images, and presses do not match -- no wonder it ws tough to get good color seps from Photoshop!

Instead of heralding this achievement, most of us were left befuddled. It took me months to get a clear picture of what had taken place, and according to one friend at Adobe, the tech-support lines nearly rang off the wall for weeks after version 5.0 shipped. Adobe had unleashed a monster, and the industry wasn't quite prepared for it.

Of the several settings added when Photoshop 5 shipped was the default conversion to CMYK into the SWOP color specifications. The RGB color default was set to sRGB (also incorrect for most professional graphic arts purposes). The Photoshop team adopted SWOP and sRGB as defaults because they were established standards at a time when no others existed. (To date there is no sheet-fed standard, though one is under development; the Adobe CMYK profiles mentioned below are the closest thing we have to an accessible standard today.) The changes to Photoshop caused a minor problem for creative professionals, but once we learned how to use the new tools, we could see that the color is visibly and measurably superior to those color separations from the pre-Photoshop 5 era.

I also applauded the developers for adopting the ICC standard for all color conversions in Photoshop, including RGB, CMYK, Lab, and the internal Working Color Spaces. For the first time it was possible to make accurate and correct color separations using Photoshop. Anyone can do it, and all you need to know is how to set some of the preferences in the application.

SWOP Stories

So the SWOP standard has been, since version 5.0 of Photoshop, the CMYK default for the program, and as a result is the standard to which color gets converted on those 90 percent of users' machines.

Yet because most print-oriented Photoshop users who create color separations print our work on sheet-fed presses, we are blindly making color separations for the wrong process. Let's look at the details.

The SWOP standard includes the following assumptions:

• Web-offset printing at high speed (20,000-60,000 impressions-per-hour);
  
  
• Heat-set drying;
  
• Semi-gloss pulp-based paper stock;
  
• 133 lpi halftone frequency;
  
• Elliptical-dot halftone patterns;
  
• 95 percent maximum shadow dot.

Hmmm. When I look down that list I notice that not even one characteristic is common to the work I prepare. I create art for high-quality sheet-fed offset with these characteristics:

• Slower press (usually less than 10,000 impressions per hour);
  
  
• Air-dried ink;
  
• Fine-gloss or dull-coated papers;
  
• High-frequency halftone (usually 150, occasionally 175 lpi) and very tight register;
  
• Modified round-dot halftone pattern;
  
• Maximum shadow dot determined by the printing process and paper.

No wonder separations don't look as good as they could when we use the SWOP settings. They're very different animals. Separations for sheet-fed printing, made with the correct profiles, are better for the sheet-fed process.

Swapping Out SWOP

As better color is very appealing to me, I want to make a proper CMYK color separation for sheet-fed printing. When you use the right separation profile, you'll get better highlights, measurably deeper shadows on glossy paper, and a larger color gamut. Making the right kind of color separation will yield a result that will make you and your client feel better about printing.

Adobe has made it easy to get it right in the more recent versions of Photoshop (6 and 7). To clarify the many color settings, recent versions of Photoshop classify them into categories of work. This makes much more sense, and guides people who use the program to choose settings that match the work they do. These are the available presets:

• Color Management Off
  
  
• ColorSync Workflow
  
• Emulate Acrobat 4
  
• Emulate Photoshop 4
  
• Europe Prepress Defaults
  
• Japan Prepress Defaults
  
• Photoshop 5 Default Spaces
  
• U.S. Prepress Defaults
  
• Web Graphic Defaults

By choosing from the list the kind of work we do (primarily prepress or Web graphics), the basic settings are closer to being correct than allowing the program to default to an unknown or incorrect set of defaults. By changing one of the defaults in the prepress defaults, I get a very good combination of settings that serves my needs well.

Here is how to do it:

1. Open the Color Settings in your Photoshop application (depending on the version, this is either under the Photoshop, File, or Edit menu).
   
2. Check Advanced Mode.
   
3. Choose U.S. Prepress Defaults from the pull-down menu entitled: Settings.
   
4. Change the Working Spaces: CMYK to U.S. Sheetfed Coated v.2 (see Figure 2). If your work is designed primarily for uncoated sheet-fed printing, you should choose U.S. Sheetfed Uncoated v.2 as your Working Space.
   
5. Save your settings (which until you save it will be called "Custom" -- give the settings a name like "My prepress defaults."
   
6. Choose the Adobe ACE engine if you prefer Adobe's software; choose Apple ColorSync (aka Heidelberg on Windows machines) if that is your preference.
   
7. Click OK, and then take the rest of the day off.

Figure 2: You can create you own custom settings as I did here, or simply use the defaults for sheet-fed presses -- coated or uncoated. Either way you'll get better results.

The two available sheet-fed profiles that come with Photoshop are extraordinarily effective. Though I prefer to use a custom profile for a particular press and paper combination if one is available, these profiles do a much better job for sheet-fed printing than SWOP will ever do.

And, next time you convert from RGB (digital camera, scanner, original art) to CMYK, from Image> Mode, you'll get a better separation from Adobe Photoshop. The results are visibly better, and should please everyone in the reproduction chain.

And, for the one percent of you who are preparing art for heat-set web-offset printing: use SWOP -- that's what it's for.

Author by Brian P. Lawler.